Speed is determined by the medium the sound travels in, and for air 1130 ft/s is generally used as the speed.

Frequency and wavelength are related, knowing the speed you can find the one of these by dividing the speed by the other. For example, 20Hz has a wavelength of 56.5ft and vice versa, and 20KHz has a wavelength of 0.0565ft and so on.

Energy level would only affect amplitude. Sound would radiate from the source in a sphereical fashion, so your formulas would need to account for that and calculate by dividing the energy evenly over the area of the sphere. If you have a single plane involved like the ground, this is one-half space so one-half the sphere's area is used, if you have two planes like the ground and a wall you use one-quarter the sphere's area. And if you're inside where you have a floor and two walls you use one-eighth the sphere's area to find the energy distribution.

Remember also that when converting energy levels to sound pressure level (SPL) that the nature of the decibel is logarithmic so keep that in mind as well.